Motorized steering column modules are known in the art that comprise one or two motors for ensuring the movement in the two control directions. In the solutions with a single motor one or several electromagnetic clutches permit the driving mechanism to be coupled in accordance with the different control modes.
Such modules permit the position of the steering wheel to be adjusted as a function of the shape and the preferences of the driver by movement in the axial and radial directions.
Movement in the axial direction allows the steering wheel to be brought closer to or further away from the driver. Radial movement is realized by tilting a part of the column along a pivoting axis perpendicular to the steering column. This allows the steering wheel to be raised or lowered.
In the solution implementing two motors each one corresponds to one of the control directions.
These motors can be constituted of rotary or linear, electric, hydraulic or pneumatic actuators. They are controlled by an electronic controller that receives instructions from contactors that allow the driver to control the different movements. The controller also receives, or receives as an alternative, instructions coming from a central controller of the vehicle for recording reference positions.
It also receives movement instructions for moving the steering wheel into a position called “easy entry”, that frees to the maximum the access to the driver's seat at each entry into and exit out of the vehicle.
DE 196 41 152 and DE 42 17 664 describe examples of known modules. The motors described are direct-current motors piloted by a control of the electromechanical relay type, static relay type or power electronic components controlled by switching. The motors are supplied with their nominal voltage for starting and during the control and are put in short-circuit for braking and stopping.
The problem posed is that transitory noises are produced during starting or stopping of the movement due to the resumption of plays, rapid deformations of the mechanical components of the control system of the steering column and the elevated torque of the motor during starting. These noises are transmitted to the passenger compartment by the steering column by its very rigid definition and are therefore very difficult to filter.